Duratech HD-8 V Series, Руководство по эксплуатации

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HD-8 SERIES V O P E R A T I N G I N S T R U C T I O N S
3.8 3.8
3.8 3.8 3.8
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There are 6 terminals on the bottom of the 518APH
Murphy relay. 12VDC power is supplied from the key
switch from the IGN terminal when the key is in the run
position. The power passes through a panel-mounted fuse
and enters the Murphy relay at terminal [B]. When the
override button is depressed, power is available at the [NC]
terminal and at the [SW1] terminal. There is a resistor
between [NC] and [SW1]. Power returns to the relay
through terminal [SW2]), which keeps the relay latched
electrically (Closed Loop circuit). The fifth terminal is the
ground [G] terminal. The sixth terminal found only on the
518APH is the [NO] terminal which will be energized
when the Murphy relay is unlatched and the key switch is
in the run position. The sixth terminal [NO] is not used on
the DuraTech Industries tub grinders.
On the Cummins engine, power must be supplied to the fuel supply valve in order for the engine to run. The fuel
supply valve is connected to the [NC] terminal of the Murphy relay so, power is only supplied to the fuel valve when
the Murphy relay button is pushed in and the key switch is in the run position. The oil pressure SWICHGAGE, the
water temperature SWICHGAGE, the tub tilt interlock system, and all engine kill buttons are connected to the Closed
Loop circuit which is connected from [SW1] to [SW2] on the Murphy relay. Any of the above controls can shut the
engine down by connecting the Closed Loop circuit to “ground” (usually a local frame ground). This will “short
circuit” the power that is emitted from [SW1] directly to ground and no power will return to [SW2]. This will cause the
Murphy relay to unlatch and power will be shut off to the fuel supply valve, causing the engine to shutdown. The
resistor in the Murphy relay reduces the voltage so arcing is minimized when a shutdown signal is activated. Also, any
“inadvertent ground” in any wire of the Closed Loop or loss of power in the Closed Loop will cause the Murphy Relay
to unlatch and the engine will shut down.
518APH-12
5700425